Li Peng, Tian Yunhe, Yang Kun, Tian Meijie, Zhu Yi, Chen Xinyu, Hu Ruiwen, Qin Tian, Liu Yongjun, Peng Shuguang, Yi Zhenxie, Liu Zhixuan, Ao Hejun, Li Juan
Hunan Soil and Fertilizer Institute, Hunan Academy of Agricultural Sciences, Changsha, 410125, China.
College of Agronomy, Hunan Agricultural University, Changsha, 410128, China.
Adv Biotechnol (Singap). 2024 Sep 19;2(4):32. doi: 10.1007/s44307-024-00038-4.
The use of nitrogen-fixing bacteria in agriculture is increasingly recognized as a sustainable method to boost crop yields, reduce chemical fertilizer use, and improve soil health. However, the microbial mechanisms by which inoculation with nitrogen-fixing bacteria enhance rice production remain unclear. In this study, rice seedlings were inoculated with the nitrogen-fixing bacterium R3 (Herbaspirillum) at the rhizosphere during the seedling stage in a pot experiment using paddy soil. We investigated the effects of such inoculation on nutrient content in the rhizosphere soil, plant growth, and the nitrogen-fixing microbial communities within the rhizosphere and endorhizosphere. The findings showed that inoculation with the R3 strain considerably increased the amounts of nitrate nitrogen, ammonium nitrogen, and available phosphorus in the rhizosphere by 14.77%, 27.83%, and 22.67%, respectively, in comparison to the control (CK). Additionally, the theoretical yield of rice was enhanced by 8.81% due to this inoculation, primarily through a 10.24% increase in the effective number of rice panicles and a 4.14% increase in the seed setting rate. Further analysis revealed that the structure of the native nitrogen-fixing microbial communities within the rhizosphere and endorhizosphere were altered by inoculation with the R3 strain, significantly increasing the α-diversity of the communities. The relative abundance of key nitrogen-fixing genera such as Ralstonia, Azotobacter, Geobacter, Streptomyces, and Pseudomonas were increased, enhancing the quantity and community stability of the nitrogen-fixing community. Consequently, the nitrogen-fixing capacity and sustained activity of the microbial community in the rhizosphere soil were strengthened. Additionally, the expression levels of the nitrogen absorption and transport-related genes OsNRT1 and OsPTR9 in rice roots were upregulated by inoculation with the R3 strain, potentially contributing to the increased rice yield. Our study has revealed the potential microbial mechanisms through which inoculation with nitrogen-fixing bacteria enhances rice yield. This finding provides a scientific basis for subsequent agricultural practices and is of critical importance for increasing rice production and enhancing the ecosystem services of rice fields.
在农业中使用固氮细菌日益被认为是一种可持续的方法，可提高作物产量、减少化肥使用并改善土壤健康。然而，接种固氮细菌提高水稻产量的微生物机制仍不清楚。在本研究中，在盆栽试验的幼苗期，于水稻根际接种固氮细菌R3（草螺菌属），使用的是稻田土壤。我们研究了这种接种对根际土壤养分含量、植物生长以及根际和根内固氮微生物群落的影响。研究结果表明，与对照（CK）相比，接种R3菌株使根际中硝态氮、铵态氮和有效磷的含量分别显著增加了14.77%、27.83%和22.67%。此外，由于这种接种，水稻的理论产量提高了8.81%，主要是通过水稻有效穗数增加10.24%和结实率提高4.14%实现的。进一步分析表明，接种R3菌株改变了根际和根内原生固氮微生物群落的结构，显著增加了群落的α多样性。关键固氮属如雷尔氏菌属、固氮菌属、地杆菌属、链霉菌属和假单胞菌属的相对丰度增加，增强了固氮群落的数量和群落稳定性。因此，根际土壤中微生物群落的固氮能力和持续活性得到增强。此外，接种R3菌株上调了水稻根中氮吸收和转运相关基因OsNRT1和OsPTR9的表达水平，这可能有助于提高水稻产量。我们的研究揭示了接种固氮细菌提高水稻产量的潜在微生物机制。这一发现为后续农业实践提供了科学依据，对增加水稻产量和提升稻田生态系统服务至关重要。
